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Topic Review (Newest First)

02-28-2011 11:25 AM

casey1999

Quote:

Originally Posted by JohnRPollard

There is no problem revving the engine in neutral. I think most of us assumed the rpms you were reporting were in neutral.

If it revs right up to 3200-3400 in neutral (I suspect it will), you have all the signs/symptoms of being over-propped. That is not good for the engine, so you should change it even if somebody else went around the world like that.

Ran the boat over the weekend. Engine air and fuel filters are new and tank fuel and strainer clean. In idle engine goes to 3400 rpm. In forward engine will only go to 2700 rpm (boat is at hull speed in 3 foot seas and 10 knot head wind). One thing I notice is that when I go to full speed in forward I get a white smoke (maybe steam) out of the exhaust. The engine is direct seawater cooled (140 deg F thermostat). The engine seems hot and about 150 deg F as measured with infered thermo.

Does this seem like a over prop situation? Hull and prop are clean. If it were over proped wouldn't I get black smoke from the exhaust? When I bring RPM to about 2200 the engine runs a little cooler and the exhaust is more clear.

11-28-2010 08:40 PM

Faster

If the engine revs fully without the cable attached at the injector pump, that would be your problem. Keep in mind that the limited throw of the cable will be at the controls end, unless it's purely cable resistance. This, however, sounds unlikely given that the throttle won't stay put ordinarily.

You can make a quick and easy throttle cable tensioner with a slit piece of small hose and a couple of hose clamps - one end tight to the outer jacket, the other adjusted over the sliding sleeve for correct tension.

11-28-2010 07:58 PM

gregw5221

Casey1999

I found this same problem in another thread, here is the link, maybe their suggestions may help you.

May be a little late now, but point of information on removing impossible zincs on my 3GM...after trying all
the penetrating products to no avail, I held a small piece of dry ice on the head of the zinc for a few minutes and was able to remove...helps to do before stripping head,
but one might be able to create a edge by grinding with
a dremmel type tool (Don't ask me how I know!)
Hope this helps...Hugo

I will give that a try. One of the plugs I have not touched so the head is still intact. The other will need some work as you mentioned to get a socket on it.
Regards, Casey

11-24-2010 02:25 PM

jrd22

After verifying that the tach readings are correct (you may not have a problem), disconnect the cable and see what rpm you can get by manually moving the throttle.

11-24-2010 02:20 PM

HUGOSALT

May be a little late now, but point of information on removing impossible zincs on my 3GM...after trying all
the penetrating products to no avail, I held a small piece of dry ice on the head of the zinc for a few minutes and was able to remove...helps to do before stripping head,
but one might be able to create a edge by grinding with
a dremmel type tool (Don't ask me how I know!)
Hope this helps...Hugo

11-24-2010 01:06 PM

casey1999

Good idea. Any idea why your engine will not make it to 3600 rpm? I sprayed my cables with silicone to lubricate, but I doubt it went very far up the cable. One problem I have is that when I move the throttle forward, it wants to come back to the idle position. Is there a way to increase the throttle resistance so that the throttle stays in the position that it is left in?
Thanks, Casey

11-24-2010 12:43 PM

gregw5221

casey1999

We had the same RPM problem on my Dad's boat with a Yanmar 2GM20F. It never seemed to get past 2300 rpms, even in neutral. We changed out the fuel filters and even had the fuel drain and cleaned the tank. Then a co-worker suggested I disconnect the trottle cable linkage from the side of the engine and manually push the lever. It worked and got the engine to 3200 rpms in neutral, the engine is rated for 3600. It looks like the previous owner had adjusted the cable to short (or long) to get the right idle speed (850) when the throttle handle is pulled all the way back.

We are going to buy a new set of throttle/clutch handles this winter and re-adjust all the cables.

Question for everyone else, do you know how to clean and grease up an existing cable?

Hope this helps!

11-06-2010 10:33 AM

sck5

the tach on my 3gm was completely worthless - i replaced it but wouldnt rely on it for testing. use one of those photo tachs to make sure you are reading what it is really doing

11-05-2010 04:57 PM

casey1999

I tried everything to get the anode out of the block- nothing worked. I tried Freeze out and did not help. The head is so rounded I think it will have to be drilled out.

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